Structure-related electrochemical behavior of sulfur-rich polymer cathode with solid-solid conversion in lithium-sulfur batteries

Abstract

Severe shuttle effect of sulfur cathodes hinders commercial application of lithium-sulfur batteries. Current technologies for sulfur cathodes by physical confinement and chemical absorptions are not enough to solve the issues of the sulfur cathodes. Organosulfur cathodes with solid-solid conversions were proposed to fundamentally avoid shuttle effect. However, in previous reports, low sulfur content and complicated electrochemical process prevent application of organosulfur cathodes in lithium-sulfur batteries. Herein, we report new solid-solid conversion based on the organosulfur cathodes in ether-based electrolytes by developing sulfur-chain controlling strategy to obtain trisulfide polymers with high sulfur content over 76 wt%. Furthermore, reaction mechanism of sulfur-based cathodes is analyzed by constructing different sulfur chains based on the strategy. Theoretical calculations suggest polymers with disulfide bonds might exhibit new lithiation behavior, which is consistent with electrochemical results. This work demonstrates new electrochemical behavior of organosulfur cathode with solid-solid conversion and show promising application prospect of these polymers.